Mask frame



FIG. 1 is a perspective view of mask frame, showing my new design;

FIG. 2 is a front view of the mask frame of FIG. 1;

FIG. 3 is a rear view of the mask frame of FIG. 1;

FIG. 4 is a top view of the mask frame of FIG. 1;

FIG. 5 is a bottom view of the mask frame of FIG. 1;

FIG. 6 is a right view of the mask frame of FIG. 1;

FIG. 7 is a left view of the mask frame of FIG. 1; and,

FIG. 8 is a perspective view of the mask frame of FIG. 1 with mask attached.

The features shown in broken lines in the FIG. 8 are for illustrating environmental structure and form no part of the claimed design. 

CLAIM The ornamental design for a mask frame, as shown and described. 